A prior invention of the present inventor entitled “a table with combined and upstanding legs” has been disclosed in Sep. 21, 2005 in the database of SIPO. The table of the prior invention includes a tabletop and a plurality of legs, the legs are upstanding and connected to the underside of the tabletop; the underside of the tabletop has connecting positions to connect with the legs, and there are screw thread holes in the connecting positions; the leg comprises a leg pipe and a ball screw, and the ball screws are inserted in the leg pipe, the first terminal of the ball screw has a protruding step, and the corresponding first terminal of the leg pipe has a slide-limited step, the protruding step of the ball screw and the slide-limited step of the leg pipe step will be blocked by each other when the ball screw and the leg pipe are cooperated. The second terminal of the screw has an external thread and passes through the second terminal of the leg pipe to bolt with a screw hole in the underside of tabletop, thus the leg pipe can be locked between the protruding step of the first terminal of the ball screw and the connection position of the underside of the tabletop. But the configuration of the invention has the following deficiency: the use of the ball screw makes the manufacture and the assembly more complicated and adds to the table cost; and the assembly and disassembly of the legs and the tabletop is inconvenient.